Sector
|
Total Effluent
|
Salt load to the environment
|
Total effluent
|
Total excl marine
|
Portion excl marine
|
Total Salt
|
Total salt excl marine
|
Portion excl marine
|
kl/day
|
kl/day
|
%
|
t/day
|
t/day
|
%
|
Paper & pulp/wood
General packaging
Steel/metals processing
Petroleum
Chemical
Power generation
Mines
Chemical suppliers
Dairy
Sugar
Canning
General food
Pharmaceutical & personal care
Animal nutrition
Poultry & meat
Beverage
Textile
Waste management
Fish processing
|
272001
1950
30500
839000
13070
132000
145025
528
2700
8100
2200
13970
1430
1205
12100
14670
6000
1909
220700
|
89001
1950
30500
69100
11070
132000
145025
528
2700
3900
2200
10970
1430
1205
12100
14670
6000
190
200
|
16.6
0.4
5.7
12.9
2.1
24.7
27.1
0.1
0.5
0.7
0.4
2.1
0.3
0.2
2.3
2.7
1.1
0.0
0.0
|
1440
2
72
354
51
158
350
0
4
10
1
11
1
1
8
11
13
5
7921
|
80
2
72
300
44
158
350
0
4
2
1
5
1
1
9
11
13
5
1
|
7.6
0.2
6.8
28.4
4.2
15.0
33.1
0.0
0.4
0.2
0.1
0.5
0.1
0.1
0.8
1.0
1.2
0.5
0.1
|
Totals
|
962239
|
534739
|
100
|
10413
|
1058
|
100
|
For general industry, effluent volumes are likely to be relatively stagnant despite anticipated future growth. This is mainly as a result of cleaner production techniques and recycling opportunities foreseen. In contrast, volumes in the gold and coal mining sectors are expected to increase significantly over the next 20 years and in particular after 2012. This trend is expected to apply in general to all mining basins (Van der Merwe et al, 2009).
The current and projected future generation of brines per major industry sector is summarized in Table 13.
Table : Current and future projected brine generation by industry sector (van der Merwe et al, 2009).
Industry sector
|
Brine (tons/day)
|
Current (2009)
|
5 year
|
10 year
|
20 year
|
Paper and Pulp/wood
|
50
|
50
|
50
|
50
|
General packaging
|
0
|
0
|
0
|
0
|
Steel/metals processing
|
240
|
240
|
240
|
240
|
Petrochemical
|
100
|
100
|
100
|
100
|
Power generation
|
1600
|
1600
|
1600
|
1600
|
Mining – Platinum
|
13
|
13
|
16
|
21
|
Mining – Gold
|
300
|
2610
|
3360
|
4350
|
Mining – Coal
|
840
|
1740
|
3240
|
11010
|
Other
|
0
|
2
|
2
|
2
|
Despite uncertainties inherent to the database (Van der Merwe et al 2009), the following specific trends was identified in the study:
-
Brine volumes generated as a result of coal and gold mining will probably represent the most important challenge over the medium term. Cumulatively, it is possible that brine volumes could be around 4000 t/d within 5 years, and as much as 15 000 t/d of brine within 20 years.
-
In terms of the areas in which brine will be generated, in the short term (depending on future strategies to manage the West and East Rand Basins) brine generation could be relatively evenly split between the Johannesburg area, and the Witbank area;
-
The greatest increase in brine generation is expected (in the longer term) to be in the area of the Witbank Coal Fields.
The data from this study informed the baseline amounts for 2011. A summary of brine treatment technology options is provided in Appendix E.
HW 14, HW 15 GW 14 and GW 15 - Ash
The categories of waste lumped together here refers to Fly ash, dusts and residues from dry gas cleaning systems as well as Bottom ash, residue from power generation, boilers and incinerators.
These waste streams are often reported as one aggregated figure. Ash generation is also not necessarily measured, but rather calculated based on combustion efficiencies. The fly ash to coarse ash ratio is a function of the type of mill used to pulverize the coal. Boilers equipped with tube mills generally produce approximately 10% coarse ash (90% fly ash) whereas boilers equipped with ball mills generally produces 20% coarse ash (80% fly ash) (Heath et al., 2009).
Approximately 90% of power generated in South Africa is generated by means of coal-fired processes (Van Zyl and Premlall, 2005) generating ash as primary waste stream. Coarse ash is damped by water sprays and the slurry is either fed to ash dams where the ash settles down and water are recycled, or it is conveyed to ash bunkers where the surplus moisture is drained off prior to discharge for disposal. Fly ash is small coal particles that did not burn completely and is separated from the flue gasses in scrubbers by means of electrostatic precipitators or bag filter systems (Heath et al., 2009).
Eskom owns 13 coal-fired power stations, the majority situated in Mpumalanga. There are also 5 smaller coal fired stations operated by either regional municipalities or Public Private Partnerships (Van Zyl and Premlall, 2005). The net capacity of ESKOM coal –fired power stations as at 31 March 2011 was 37 745 MW (ESKOM, 2011). The ESKOM coal-fired power stations are fully operated at all times i.e. on a 24 hour basis. Municipal and private power stations add another 900 MW (Van Zyl and Premlall, 2005).
In the order of 25 million tons of combustion fly ash is produced annually, most of which is disposed on land in ash dams or ash dumps (Heath et al, 2009). Approximately 1.2 million tons of fly ash per year is sold to amongst others, the cement industry (Heath et al., 2009).
The net power generating capacity of the coal-fired power stations is summarized in Table 14.
Table : Net power Generating capacity of Coal-fired power stations (Van Zyl and Premlall, 2005; Eskom, 2011)
Power stations
|
Net Maximum Capacity (MW)
|
ESKOM
|
37745
|
Municipal and Private
|
900
|
Total
|
38645
|
The actual power generation and ash production by the ESKOM coal-fired power stations are summarized in Table 15.
Table : Power generation and ash production by ESKOM coal-fired power stations over time (Eskom, 2011)
Year
|
Total electricity produced by ESKOM coal-fired power stations
GWh(net)
|
Ash produced (Mt)
|
2007
|
215211
|
34.16
|
2008
|
222908
|
36.04
|
2009
|
211941
|
36.66
|
2010
|
215940
|
36.01
|
2011
|
220219
|
36.22
|
The data reported in the baseline is a combination of ESKOM data and data obtained from relevant waste management companies.
Future projections of ash production by ESKOM should take cognizance of the following expansions (ESKOM, 2012):
-
Medupi will add a capacity of 4 764 MW (6 units) with the first unit to be opened in 2012 and the last in 2015.
-
Kusile will add a capacity of 4 800 MW (6 units) with the first unit opening in 2014 and the last in 2018. Kusile will also generate Flue Gas Desulphurisation sludge.
-
ESKOM plans to double its capacity by 2026 to 80 000 MW, although a proportion of the new capacity will be provided by gas fired or nuclear energy plants.
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